1. Field of the Invention
This invention relates to centrifugal pumps, and the like, of the type having a volute axially movable within a barrel, and in particular to an improved spacer for regulating the separation between the volute and an inside surface of the end barrel cover.
2. Description of the Prior Art
One of the most difficult design problems in building a reliable centrifugal pump involves obtaining a proper and long-lived seal between the high pressure and low pressure sections of the pump. In applications requiring the pump to handle water under high pressure and high temperature conditions, these design objectives are even more critical since downtime of the centrifugal pump often means large repair expenses and causes downtime for even more expensive and more critical machines dependent on the operation of a centrifugal pump.
Centrifugal pumps are generally constructed with an outside barrel having a cylindrical cavity for receiving therein a generally cylindrical volute. The volute includes a plurality of cavities for receiving therein the rotary blades which are coupled to an impeller shaft which communicates through the volute and barrel. The high pressure and low pressure sections of the centrifugal pump are separated by a specially designed annular seal. As the centrifugal pump is operated, the high pressure acting upon one end of the volute compresses the seal. However, when the output of the centrifugal pump is reduced, the reduction in output pressure will allow a reverse direction movement in the volute as it presses against the annular seal. This movement eventually allows a leakage path between the high pressure and low pressure sections of the centrifugal pump which allows leaking water to erode away sections of the volute and barrel adjacent to the annular seal. This causes a reduction in output pressure from the pump and can lead to serious reliability problems.
Various methods have been utilized for restricting this reverse motion of the volute, but none have been acceptable in all respects. McHugh in U.S. Pat. No. 2,017,544 discloses the flexible seal which is provided between the shell casing of the pump and the starter parts thereof. This flexible seal uses axially aligned springs which are utilized to compress the volute against the seal. Other devices relating to centrifugal pumps or compressors are disclosed by Davis in U.S. Pat. No. 3,325,087, Johnson in U.S. Pat. No. 2,867,460 and Hall in U.S. Pat. No. 2,247,125.
Martinson, in U.S. Pat. No. 2,777,665, dicloses an improved method for supporting a turbine casing which will allow the turbine casing to expand and contract relative to the pedestal without changing the relative position between the casing and the shaft extending therethrough and into the bearing support mounting in the pedestal.